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MAINE DEPARTMENT OF
CONSERVATION
Maine Forest Service
Forest Health & Monitoring Division
Links to: Issue 1 - May 13, 2002 Issue 2 - June 5, 2002 Issue 3 - June 26, 2002
It doesn't seem possible that Fall is upon us, but as we head into another school year with summer vacation behind us, and hints of fall coloration confronting us we need to begin lining up those fall chores. Most of our late season insects will fall more into the nuisance category but some serve to remind us of what could lie ahead for 2003. With drought to near-drought conditions across the state you may wish to provide moisture to trees and shrubs as winter approaches to help alleviate further moisture stress during warm winter periods. Heavy beech nut production and cone production on balsam fir and spruce could also stress respective hosts.
The following highlights should give you an idea of where we stand and some things to consider on pest species.
This is our fourth and probably last, seasonal issue for 2002. Keep in touch and have a great winter!
Insects
Alder Flea Beetle (Altica ambiens alni) - Although drought stress has affected many alder thickets across central and southern Maine, it has been the blue-black larvae of this beetle which has browned up many of the lowland pockets of alder. The metallic blue/green beetles are now moving about, aggregating and will soon head for hibernation sites in buildings, rock piles, hollow trees and forest litter.
Arborvitae Leafminers (a complex of four species) - Arborvitae across much of central and eastern Maine look terrible this season due to feeding by the leafminer, some borer/bark beetle activity and drought stress. Hedges that have been treated and watered generally look good. At this point another generation of leafminers have started mining but will soon cease for the winter.
Bark Beetles (various) - Reports of activity of the pine engraver (Ips pini) and red turpentine beetle (Dendroctonus valens) on pines seem to be more common this season than they have for several years. The spruce beetle (Dendroctanus rufipennis) continues to infest new spruce while the eastern larch beetle (Dendroctonus simplex) is taking out increasing numbers of stressed larch.
Balsam Woolly Adelgid (Adelges piceae) - Increasing mortality of balsam fir initiated by the feeding activity of this introduced pest continues to affect the fir resource especially in coastal Hancock and Washington counties and locally north to Medway.
*Birch Leafminers ( Primarily Messa nana with some Profenusa thomsoni) - Birch foliage infested by one or both of these species of leafminer and drought looked off color tan/yellow by early August and some leaf drop has now begun.
*Browntail Moth (Euproctis chrysorrhoea) - Populations appear healthy at this time and winter webs are now forming. Heavy damage was again restricted to traditional coastal areas around Casco Bay where 2,000 acres were treated in municipal programs and many more under private contract with ground applicators. Rapid refoliation and the unavailability of survey aircraft at the right time prevented aerial mapping this season. The bad news is that the warm weather has apparently allowed increasing populations to occur inland several miles. Durham has a significant population as well as interior portions of Cumberland. Reports have been received of this insect in Windsor and Augusta as well but they are not in damaging numbers at this time. Surveys of overwintering web distribution and abundance should be done after most leaves have dropped in December or later. Removal and destruction of overwintering webs may help reduce future populations in some cases.
*Fall Webworm (Hyphantria cunea) - The filmy tents of this species are now very visible on a wide variety of deciduous trees across the state. These tents which include foliage and feeding larvae, are enlarged as the larvae grow. When high numbers occur trees can be stripped. Tents are most common on alder, apple, ash, beech, birch, cherry, elm and oak. Populations appear to have dropped off noticeably in many areas this season but may be locally heavy.
*Gypsy Moth (Lymantria dispar) - Gypsy moth populations suffered heavily this season from diseases caused by the fungus Entomophaga maimaiga and virus with a scattering of parasites in later larval stages. Early season estimates of expected defoliation of 150,000 acres dropped to around 25,000 acres as the season progressed. Defoliation was very heavy around Sanford east to Kennebunk and north to the Buxton area as well as 2,000 to 3,000 acres in the Baring area. No live larvae were seen in ground checks of the Baring area and E. maimaiga was very active! Numerous homeowner complaints were received from the Turner area as well although primarily light to moderate defoliation was observed in associated surveys. Winter egg mass surveys will begin after leaf drop.
Hardwood Defoliators (late season) - We have received no reports of late season defoliator activity except what you see here. In many cases there is very little green foliage now to feed on!
*Hemlock Looper (Lambdina fiscellaria) - Hemlock looper populations dropped noticeably this season and defoliation ran from trace to light in most stands with only a few hot spots showing moderate to heavy damage. Some local tree mortality was observed especially in York County. The frail, grayish/tan adult moths of this species have begun to fly in infested stands and should be noticeable through mid to late September. The activity of moths of this and other loopers can occur through hunting season and these Hunter's Moths can give evidence of future populations.
*Hemlock Woolly Adelgid (Adelges tsugae) - (HWA) is a serious pest of hemlocks that has been found and eradicated in planted hemlocks in Maine but has never been found in any of our native hemlocks. Since 1999 this pest has been found in 120 planted hemlocks that are linked to tree shipments from infested areas in other states. In 2002 HWA was detected in 21 trees on 10 landscape sites in the towns of Lubec, Bar Harbor, Camden, Rockland, Southport, Kittery Point, York and York Harbor. With the exception of the sites in Lubec and Southport which are still in the process of being treated, all infested trees have been removed and destroyed.
The Maine Forest Service Insect and Disease Laboratory continues to monitor planting sites where this pest was eradicated and also seeks the help of the general public in looking for signs of this pest in planted hemlock trees in their yards. The most conspicuous sign of the pest are the white masses of wool produced by the insect along the young twigs. These wool masses resemble cotton swab tips and are present during most of the year. Anyone who sees signs of the insect on their hemlock should contact Don Ouellette, Insect & Disease Laboratory, 50 Hospital Street, Augusta, ME 04330, Tel: 207-287-2431 or email don.ouellette@state.me.us.
Larch Sawfly (Pristiphora erichsonii) - Larvae of this species seemed to appear later than expected and were more spotty as well. Highest populations and expected defoliation have been observed from central Penobscot county through eastern Aroostook county. Defoliation in central Maine and "Downeast" appears to be more spotty.
Locust Leafminer (Odontota dorsalis) - Black locust across southern Maine are now very brown due primarily to the mining activities of this beetle. The somewhat flat, longitudinally striped black and reddish-orange beetles are now active in great numbers and will soon seek hibernation sites.
*Oak Twig Pruner (Anelaphus parallelus) - Flags (hanging twigs and branches with brown leaves) mined and pruned by this or a related species, A. villosus are a common site on both oak and maple across much of southern and central Maine. Damage is usually heaviest in alternate years, which this is. In a windy season most of the flags drop by late August. Damage to host trees is minimal.
Tussocks (various) - As fall approaches the fuzzy caterpillars which often appear are picked up by children who may handle them somewhat roughly. The more familiar red and black banded woollybear caterpillars (Pyrrharctia isabella) do not seem to cause any irritation and these make nice "pets." It is the hickory tussock (Lophocampa caryae), rusty tussock (Halysidota tessellaris), spotted tussock (Lophocampa maculata) and whitemarked tussock (Orgyia leucostigma), which easily release their hairs, that cause the most serious rashes or "tussockosis." Low numbers of these tussocks occur every year but occasionally spot infestations do occur and it is then that the caterpillars and their fuzz-ball like cocoons should be avoided. Fortunately, the impact of "tussockosis" is usually of short duration and relief is more easily achieved unlike the toxin related rash of the browntail moth of Casco Bay.
Viburnum Leaf Beetle (Pyrrhalta viburni) - Adults are now active on infested viburnum. Control of the adults with carbaryl in August may help reduce egg deposition and subsequent shoot mortality and larval populations another year. Cutting and destruction of shoots with eggs in the fall should also help.
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Insect and Disease Laboratory, 50 Hospital Street, Augusta, Maine
04330-6514
Phone (207) 287-2431, Fax (207) 287-2432.
Compiled by Richard
G. Dearborn and Clark A. Granger
02-4 Forest Health & Monitoring Division Augusta, Maine
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